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delegation: store child segment flag in PathSegment#158556

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aerooneqq:delegation-child-segment-perf
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delegation: store child segment flag in PathSegment#158556
aerooneqq wants to merge 1 commit into
rust-lang:mainfrom
aerooneqq:delegation-child-segment-perf

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@aerooneqq aerooneqq commented Jun 29, 2026

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This should reduce perf overhead of checking whether path segment is a delegation's child segment.

r? @petrochenkov

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 29, 2026
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petrochenkov commented Jun 29, 2026

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@bors try @rust-timer queue

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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 29, 2026
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rust-bors Bot pushed a commit that referenced this pull request Jun 29, 2026
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Auto merge of #158556 - aerooneqq:delegation-child-segment-perf, r=<try>
ab95f53 
delegation: store child segment flag in `PathSegment`
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☀️ Try build successful (CI)
Build commit: ab95f53 (ab95f53da0952e11b0180d3d6de83e807f1ec82b)
Base parent: 63f05e3 (63f05e3635171e7ac3f9ca78bad6c71052cda5a3)

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rust-timer commented Jun 29, 2026

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Finished benchmarking commit (ab95f53): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

This perf run didn't have relevant results for this metric.

Cycles

This perf run didn't have relevant results for this metric.

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 486.982s -> 486.289s (-0.14%)
Artifact size: 393.22 MiB -> 393.15 MiB (-0.02%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 29, 2026
@aerooneqq

aerooneqq commented Jun 29, 2026

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There are no significant improvements, but many insignificant with significance factor 0.6 - 0.8, including typenum-1.18.0 which in regression PR had:

▶ typenum-1.18.0 check incr-full llvm x64 0.11% 0.03% 4.12x
▶ typenum-1.18.0 opt incr-full llvm x64 0.11% 0.03% 4.18x
▶ typenum-1.18.0 debug incr-full llvm x64 0.11% 0.02% 4.63x

And in this PR:

▶ typenum-1.18.0 check incr-full llvm x64 -0.12% 0.16% 0.79x
▶ typenum-1.18.0 opt incr-full llvm x64 -0.12% 0.18% 0.68x
▶ typenum-1.18.0 debug incr-full llvm x64 -0.12% 0.18% 0.68x

So I think we can consider perf regression from #157960 to be resolved here.

@rustbot ready

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 29, 2026
@aerooneqq aerooneqq marked this pull request as ready for review June 29, 2026 13:19
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rustbot commented Jun 29, 2026

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HIR ty lowering was modified

cc @fmease

petrochenkov
petrochenkov reviewed Jun 29, 2026
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Comment thread compiler/rustc_hir/src/hir.rs
/// Whether this segment is a delegation's child segment:
/// `reuse Trait::foo`, in this case `foo` is a delegation's child segment.
/// Used for faster check during generic args lowering.
pub delegation_child_segment: bool,

@petrochenkov petrochenkov Jun 29, 2026 •
edited by rustbot
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Note: the PathSegment's size doesn't change, there's a corresponding assert at the bottom of the file.

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Comment thread compiler/rustc_hir/src/intravisit.rs Outdated
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petrochenkov commented Jun 29, 2026

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r=me after addressing #158556 (comment).
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@rustbot rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 29, 2026
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rust-bors Bot commented Jun 29, 2026

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✌️ @aerooneqq, you can now approve this pull request!

If @petrochenkov told you to "r=me" after making some further change, then please make that change and post @bors r=petrochenkov.

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@rustbot rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 29, 2026
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rustbot commented Jun 29, 2026

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Reminder, once the PR becomes ready for a review, use @rustbot ready.

@petrochenkov petrochenkov mentioned this pull request Jun 29, 2026
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@aerooneqq aerooneqq force-pushed the delegation-child-segment-perf branch from 2bee069 to 91a762b Compare June 29, 2026 13:54
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aerooneqq commented Jun 29, 2026

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@bors r=petrochenkov

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rust-bors Bot commented Jun 29, 2026

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📌 Commit 91a762b has been approved by petrochenkov

It is now in the queue for this repository.

@rust-bors rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 29, 2026
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